Creep Influence On Static And Dynamic Reliability Of Long-Span Concrete Filled Steel Tube Arch Bridges

Rapid development of concrete filled steel tube (CFST) arch bridges is inevitably accompanied by special attention paid to the issue of long-term performance, which is significantly influenced by concrete creep. Further carrying out the theoretical research on creep effects of CFST arch bridges, in terms of breadth, means that the understanding on structural creep effects should be expanded from static area to dynamic area; in terms of deapth, means that the study on creep effects should be extended from deterministic area to probabilistic area, and be from the angle of reliability. In view of the two points mentioned above, this paper focuses on the influence of creep on the static reliability, random vibration response and dynamic reliability of CFST arch bridges.Based on creep test data and a micro constitutive model of concrete creep, this paper proposes creep models for concrete containing silica fume or fly ash. On the basis of the material models, creep of CFST columns is analyzed by numerical method.In the field of creep effect on static behaviors of structures, this paper presents a probability analysis to investigate the creep effect on structural serviceability reliability by Monte Carlo simulation with Latin Hypercube sampling method, considering random variables involved in three aspects:creep model uncertainty and variations of material and geometrical properties.In the field of creep effect on dynamic behaviors of structures, this paper analyzes the relationships between instantenous and sustained loadings, and between instantenous and long-term responses, and explains the mechamism of creep influence on structural dynamic behavior. According to tests on concrete mechamical properties after a sustained loading, this paper develops a model to predict elastic modulus of concrete having subjected to the effect of sustaind loading. Based on this, this paper analyzes the creep influence on structural dynamic properties, deterministic dynamic responses and random dynamic responses. In accordance with first-passage failure criterion, this paper finally assesses the creep influence on the dynamic reliability of CFST arch bridges.